1. Field of Invention
This invention relates to single hand operated load carrying devices, specifically those having a pair of gripping jaws.
2. Prior Art
Of all the ancient tasks performed by humans, the employment of both human arms and hands in the grasping, lifting and carrying of objects having opposed parallel surfaces is probably one of the oldest. Even in our modern times, product distribution and delivery needs require an endless list of items to be packaged in containers meant to be carried by hand. These items include consumable goods, appliances, medicines, food, apparel, liquids, mail etc.
The manual lifting and transporting of these packages is a task built into the design of work stations and handling procedures found in common workplace. This is true even when studies show that many job related back injuries result from the application of improper or excessive effort during the performance of such tasks. Many object carrying devices have been designed to assist in the grasping, lifting and carrying of objects. However, in some instances, the devices are awkward to operate, requiring additional time or effort from the part of the end user. In other instances, the devices are invasive to the object's surfaces and their use would compromise the object's integrity or aesthetics. Let's review some of these devices.
Prior art, in the single hand operated carrying devices, concerned itself with scissor-like lifting devices with limited adjustment capability and with tools that relay on penetrating the object's surface to achieve a non-friction grip. In U.S. Pat. No. 4,109,952 to Monzain, issued on Aug. 29, 1978, a package lifter includes pivoted jaws levers for achieving flat engagement with the side walls of a package. Although such jaw levers have padded members meant to achieve a friction grip, protruding metal teeth need to be positioned underneath the package to achieve the grip. This teeth positioning under the package lends itself to be difficult and awkward. In addition, the height of the package to be lifted is limited to that of the physical length of the jaw levers.
Another example of a scissor-like device is the type of carrier tools used to carry automotive batteries. Such a device is U.S. Pat. No. 4,678,217 issued to Viola et al. Jul. 7, 1987. The carrier tool is used to grasp and carry automotive batteries employing a single hand. The scissor-like configuration of this tool conveniently utilizes the battery's own weight to produce lateral opposing forces to grip the battery. However, the metal teeth on the convex curvature of the jaw's inner surface provide an extremely limited contact surface area between the device and the battery. Substantial pressure must be concentrated at these contact points in order to hold the battery, greatly increasing the possibility of damaging the battery's surfaces. In addition, the carrier tool lacks a slip joint pivot connection of the jaw levers, which limits its use to a very narrow range of object widths.
What is needed is an easily attachable/detachable device that does not require engaging the underside of the object. Objects meant to be carried using both human arms and hands come in a variety of widths and heights. Consequently, the use of a carrying device should not be limited to a narrow range of object's heights or widths. Furthermore, a friction grip carrying device should provide a surface contact area similar to that provided by both human hands. This allows the gripping pressure to be uniformly distributed and to avoid object surface damage.
Among the prior art achieving a non-friction grip there is U.S. Pat. No. 5,871,242 issued to Whitney on Feb. 16, 1999. This lifting device comprises a pair of grips operated by a single hand and actuating a set of jaws substantially at a right angle from each other. The gripping force is not of the friction-grip type or exerted against the object's opposed surfaces. Therefore, the jaws have projections that are meant to pierce, puncture or penetrate, at some degree, the surface of the object to be lifted. Package integrity and aesthetics would be compromised by this piercing, puncturing or penetration.
An embodiment of the device requires a constant hand squeezing force to maintain the grip upon the object. Another embodiment provides a feature for locking the jaws in place, so this constant hand squeezing force is not required while transporting a carton. However, the inclusion of this feature requires two different device designs: one for right-handed persons and one for left-handed persons. Finally, the use of the device is limited to objects having a pair of flat surfaces essentially at a right angle from each other, and of a material that can be pierced, punctured or penetrated by the projections.
Another single hand operated gripping tool of the non-friction grip type is that of U.S. Pat. No. 6,375,237 issued to Koenig, Apr. 23, 2002. As with Whitney's carton lifting device, this tool relies on penetrating the carton skin to achieve a grip. It is, however, different to Whitney's carton lifting device in that a pair of gripping plates has handles meant to be squeezed together for package release. Since these handles are also used to carry the object, this configuration greatly increases the possibility of accidental opening of the gripping plates and dropping of the load while being transported.
What is needed is a carrying device that could be used to carry objects with hard surfaces, like those of a T.V. set, as well as objects having soft surfaces that should not be scratched or damaged in any way. Furthermore, it is needed a device with a standard, reliable and automatic locking mechanism that does not require a constant hand squeezing force and that will not allow the accidental release of the object during transport.
Other devices like U.S. Pat. No. 4,055,364 issued to Breite on Oct. 25, 1977, for the carrying of automotive batteries have a slip joint pivot connection of the gripping legs and a grip locking mechanism. Although the device allows the carrying of the battery using a single hand, the locking mechanism and the adjustment of the gripping legs against the battery's opposed surfaces, requires the use of both human hands.
What is needed is a non-invasive carrying device that can be adjusted and locked against the opposed parallel surfaces of an object using a single human hand. It is needed a carrying device that not only allows the single handed lifting and carrying of an object, but one that also allows a single handed release of the object after, and only when, it has been safely placed on a surface. No such device as just described is known to presently exist.